U.S. patent number 10,562,565 [Application Number 16/314,637] was granted by the patent office on 2020-02-18 for steering control method and system of self-driving vehicle.
This patent grant is currently assigned to UISEE TECHNOLOGIES (BEIJING) LTD. The grantee listed for this patent is UISEE TECHNOLOGIES (BEIJING) LTD. Invention is credited to Yan Jiang, Sai Luo, Jinzhan Peng, Dan Zhang, Xiaocheng Zhou, Xin Zhou.
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United States Patent |
10,562,565 |
Jiang , et al. |
February 18, 2020 |
Steering control method and system of self-driving vehicle
Abstract
A steering control method and a steering control system for
self-driving of a vehicle are disclosed. The method comprises
obtaining information about an expected steering angle of a vehicle
based on an automatic planning control operation; detecting whether
an effective torque is applied to a steering wheel by a driver; and
when it is detected that the driver has applied the effective
torque to the steering wheel, computing a difference between a
turning angle of the steering wheel controlled by the driver and
the expected steering angle of a vehicle, and determining a
self-driving intent prompt torque according to the difference
between the two, wherein the self-driving intent prompt torque is
to be applied to a steering system.
Inventors: |
Jiang; Yan (Beijing,
CN), Peng; Jinzhan (Beijing, CN), Zhou;
Xin (Beijing, CN), Zhang; Dan (Beijing,
CN), Zhou; Xiaocheng (Beijing, CN), Luo;
Sai (Beijing, CN) |
Applicant: |
Name |
City |
State |
Country |
Type |
UISEE TECHNOLOGIES (BEIJING) LTD |
Beijing |
N/A |
CN |
|
|
Assignee: |
UISEE TECHNOLOGIES (BEIJING)
LTD (Beijing, CN)
|
Family
ID: |
59927630 |
Appl.
No.: |
16/314,637 |
Filed: |
July 5, 2016 |
PCT
Filed: |
July 05, 2016 |
PCT No.: |
PCT/CN2016/088559 |
371(c)(1),(2),(4) Date: |
December 31, 2018 |
PCT
Pub. No.: |
WO2018/006261 |
PCT
Pub. Date: |
January 11, 2018 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20190337561 A1 |
Nov 7, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Jul 5, 2016 [WO] |
|
|
PCT/CN2016/088559 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B62D
6/002 (20130101); B62D 1/286 (20130101); B62D
6/10 (20130101); B62D 6/08 (20130101) |
Current International
Class: |
B62D
6/10 (20060101); B62D 6/00 (20060101); B62D
1/28 (20060101); B62D 6/08 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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101734278 |
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Jun 2010 |
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CN |
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102307774 |
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Jan 2012 |
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CN |
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103419839 |
|
Dec 2013 |
|
CN |
|
103921841 |
|
Jul 2014 |
|
CN |
|
102010048913 |
|
Jun 2011 |
|
DE |
|
2004299604 |
|
Oct 2004 |
|
JP |
|
2014205457 |
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Oct 2014 |
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JP |
|
2016006013 |
|
Jan 2016 |
|
WO |
|
Other References
PCT, International Search Report for PCT Application
PCT/CN2016/088559, dated Apr. 1, 2017, 4 pages. cited by applicant
.
PCT, Written Opinion of the International Searching Authority for
International Application No. PCT/CN2016/088559 filed Jul. 5, 2016
(Chinese and English translation attached), 6 pages. cited by
applicant .
Supplemental European Search Report for European Patent Application
No. EP16907766 dated May 31, 2019, 6 pages. cited by
applicant.
|
Primary Examiner: Black; Thomas G
Assistant Examiner: Li; Ce Li
Attorney, Agent or Firm: MagStone Law LLP
Claims
What is claimed is:
1. A method for self-driving a vehicle, comprising: obtaining
information about an expected steering angle of the vehicle based
on an automatic planning control operation; detecting whether an
effective torque is applied to a steering wheel by a driver;
determining a self-driving intent prompt torque, comprising: in
response to detecting that the driver has applied the effective
torque to the steering wheel, computing a difference between a
turning angle of the steering wheel controlled by the driver and
the expected steering angle of the vehicle; and determining a
self-driving intent prompt torque according to the difference,
wherein the self-driving intent prompt torque is to be applied to a
steering system of the vehicle; determining a reliability status of
operations of a self-driving system; increasing the self-driving
intent prompt torque determined according to the difference in
response to determining that the reliability status of operations
of the self-driving system is a high-reliability status; and
decreasing the self-driving intent prompt torque determined
according to the difference in response to determining that the
reliability status of operations of the self-driving system is a
low-reliability status.
2. The method according to claim 1, wherein determining the
self-driving intent prompt torque according to the difference
comprises: determining a larger self-driving intent prompt torque
when the difference is larger, wherein the self-driving intent
prompt torque is opposite to a torque that the driver needs to
provide, and wherein the torque that the driver needs to provide is
larger if the difference is larger.
3. The method according to claim 2, further comprising: applying a
steering torque to the steering wheel, wherein when the driver has
applied the effective torque to the steering wheel, the steering
torque applied to the steering wheel comprises a steering torque
applied by the driver, a steering assistance torque of a vehicle
steering assistance system, and the self-driving intent prompt
torque.
4. The method according to claim 3, wherein the self-driving intent
prompt torque is determined based on the following formula:
.tau..sub.c =-sig(.tau..sub.driver)f(fabs(.DELTA..beta.)) wherein
.tau..sub.c is the self-driving intent prompt torque, wherein
.DELTA..beta. is determined based on the following formula:
.DELTA..beta.=.beta..sub.e-.beta..sub.driver, wherein
.tau..sub.driver denotes a torque currently applied by the driver,
.beta..sub.e denotes an expected turning angle of self-driving,
.beta..sub.driver denotes a turning angle where the steering wheel
is located, and sig(.tau..sub.driver) denotes a direction of the
torque currently applied by the driver; wherein f is a positive
correlation function of an absolute value of .DELTA..beta. and
satisfies the following conditions:
.function..ltoreq..times..times..function..tau..ltoreq..times..times..fun-
ction..tau. ##EQU00005## wherein .tau..sub.eps denotes the steering
assistance torque, and fabs(.tau..sub.c) denotes an absolute value
of .tau..sub.c.
5. The method according to claim 1, wherein the method for
determining the reliability status of operations of the
self-driving system comprises: determining the reliability status
of operations of the self-driving system based on a complexity of a
current self-driving road environment and a severity of a lighting
condition.
6. A system for controlling a vehicle, comprising: an expected
vehicle steering angle computation unit configured to obtain
information about an expected steering angle of the vehicle based
on an automatic planning control operation; a driver's operation
detection unit configured to detect whether an effective torque has
been applied to a steering wheel by a driver; a self-driving intent
prompt torque determination unit configured to: computing a
difference between a turning angle of the steering wheel controlled
by the driver and the expected steering angle of the vehicle in
response to detecting that the driver has applied the effective
torque to the steering wheel; and determining a self-driving intent
prompt torque according to the difference, wherein the self-driving
intent prompt torque is to be applied to a steering system of the
vehicle; and a self-driving system operating state determination
unit configured to: determine a reliability status of operations of
a self-driving system; increase the self-driving intent prompt
torque determined according to the difference in response to
determining that the reliability status of operations of the
self-driving system is a high-reliability status; and decrease the
self-driving intent prompt torque determined according to the
difference in response to determining that the reliability status
of operations of the self-driving system is a low-reliability
status.
7. The system of claim 6, wherein, to determine the self-driving
intent prompt torque according to the difference, the driver's
operation detection unit is further to: determine a larger
self-driving intent prompt torque when the difference is larger,
wherein the self-driving intent prompt torque is opposite to a
torque that the driver needs to provide, and thus, if the
difference is larger, the torque that the driver needs to provide
is larger.
8. The system of claim 6, wherein the system is further to apply a
steering torque to the steering wheel, wherein when the driver has
applied the effective torque to the steering wheel, the steering
torque applied to the steering wheel comprises a steering torque
applied by the driver, a steering assistance torque applied by a
vehicle steering assistance system and the self-driving intent
prompt torque.
9. The system of claim 8, wherein the self-driving intent prompt
torque determination unit determines the self-driving intent prompt
torque based on the following formula:
.tau..sub.c=-sig(.tau..sub.driver)f(fabs(.DELTA..beta.)) wherein
.DELTA..beta. is determined based on the following formula:
.DELTA..beta.=.beta..sub.e-.beta..sub.driver wherein
.tau..sub.driver denotes a torque currently applied by the driver,
.beta..sub.e denotes an expected turning angle of self-driving,
.beta..sub.driver denotes the turning angle of the steering wheel,
and sig(.tau..sub.driver) denotes a direction of the torque
currently applied by the driver; wherein f is a positive
correlation function of an absolute value of .DELTA..beta. and
satisfies the following conditions:
.times..times..function..ltoreq..times..times..function..tau..ltoreq..tim-
es..times..function..tau. ##EQU00006## wherein .tau..sub.eps
denotes the steering assistance torque, and fabs(.tau..sub.c)
denotes an absolute value of .tau..sub.c.
10. The system of claim 6, wherein the self-driving system
operating state determination unit is further configured to:
determine the reliability status of operations of the self-driving
system based on a complexity of a current self-driving road
environment and a severity of a lighting condition.
11. The system of claim 6, further comprising: an automatic
steering control unit configured to control the turning angle of
the steering wheel to reach the expected steering angle of the
self-driving system in response to detecting that the driver has
not applied the effective torque to the steering wheel.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national phase application of International
Application No. PCT/CN2016/088559, filed on Jul. 5, 2016, which is
hereby incorporated by reference in its entirety.
FIELD OF THE INVENTION
The present invention relates to the field of vehicle control, in
particular to a steering control method and a steering control
system for self-driving of a vehicle.
BACKGROUND
The development of vehicle technologies has facilitated productions
and implementation of self-driving vehicles.
In an existing steering control system of a self-driving vehicle, a
planning control system in the self-driving system computes a
desired turning radius of the vehicle based on a sensing
positioning result, and a steering wheel is rotated to a determined
position under turning angle control.
Existing electric power steering (EPS) systems of vehicles may
apply a steering assistance torque according to a driver's
operations on the steering wheel to help the driver to turn the
steering wheel with a small torque.
SUMMARY OF THE INVENTION
The inventors analyzed steering control systems of existing
self-driving vehicles and concluded that ultimately the steering
control systems aim to control the steering wheel to reach an
expected turning angle no matter torque control or turning angle
control is used. As a result, when the driver wants to intervene in
the driving process, he must conflict with the self-driving system
and grab the control on the steering wheel from the manipulator,
which is not an ideal way to switch between manual driving and
self-driving. As such, the existing self-driving systems can only
work independently and cannot work in harmony with a human driver.
This is because, in the conventional technology, when the expected
turning angle of the self-driving system conflicts with the
expected turning angle of the human driver, the self-driving system
tries to cause the steering wheel to reach the expected turning
angle (which means a deviation from the operation of the human
driver), or exits the self-driving state (which means manual
intervention to regain the control on the vehicle).
However, an existing EPS system of a vehicle can assist the driver
only by means of the driver's input and cannot implement an active
self-driving function.
The objective of the present invention is to overcome the
disadvantages and shortcomings in the prior art, and to propose a
new steering control method and a steering control system for
self-driving of a vehicle so that the driver and the self-driving
system jointly participate in the driving process.
According to an aspect of the present invention, a steering control
method for self-driving of a vehicle is provided, specifically
including:
firstly, a step for computing an expected vehicle steering angle,
comprising obtaining information about an expected steering angle
of a vehicle based on an automatic planning control operation;
secondly, a step for detecting a driver's steering wheel operation,
comprising detecting whether an effective torque is applied to a
steering wheel by a driver; and
thirdly, a step for determining a self-driving intent prompt
torque, comprising: when it is detected that the driver has applied
the effective torque to the steering wheel, computing a difference
between a turning angle of the steering wheel controlled by the
driver and the expected steering angle of the vehicle, and
determining a self-driving intent prompt torque according to the
difference, wherein the self-driving intent prompt torque is to be
applied to a steering system.
Further, the step of determining a self-driving intent prompt
torque according to the difference may specifically include:
determining a larger self-driving intent prompt torque when the
difference between the turning angle of the steering wheel
controlled by the driver and the expected steering angle of the
vehicle is larger, wherein the self-driving intent prompt torque is
opposite to a torque that the driver needs to provide. Hence, if
the difference is larger, the torque that the driver needs to
provide is larger.
Further, when the driver has applied the effective torque to the
steering wheel, the steering torque applied to the steering wheel
may include a steering torque applied by the driver, a steering
assistance torque of a vehicle steering assistance system, and the
self-driving intent prompt torque.
Further, the self-driving intent prompt torque .tau..sub.c may be
determined based on the following formula:
.tau..sub.c=-sig(.tau..sub.driver)f(fabs (.DELTA..beta.)), wherein
.DELTA..beta. may be determined based on the following formula:
.DELTA..beta.=.beta..sub.e-.beta..sub.driver
wherein .tau..sub.driver denotes a torque currently applied by the
driver, .beta..sub.e denotes an expected turning angle of
self-driving, .beta..sub.driver denotes a turning angle where the
steering wheel is located, and sig(.tau..sub.driver) denotes the
direction of the torque currently applied by the driver;
f is a positive correlation function of absolute value of
.DELTA..beta. and may satisfy the following conditions:
.times..function..ltoreq..times..times..function..tau..ltoreq..times..ti-
mes..function..tau. ##EQU00001##
wherein .tau..sub.eps denotes a steering assistance torque.
Moreover, the method may further include a step of determining a
reliability status of operations of the self-driving system,
specifically including:
in response to determining that an operating status of the
self-driving intent prompt torque is a high-reliability status,
increasing the self-driving intent prompt torque determined
according to the difference between the two and outputted by a
steering controller in the self-driving intent prompt torque
determination step; or
in response to determining that the operating status of the
self-driving system is a low-reliability status, decreasing the
self-driving intent prompt torque determined according to the
difference between the two and outputted by the steering controller
in the self-driving intent prompt torque determination step.
Further, the method for determining the reliability status of the
operations of the self-driving system may be based on a complexity
of a current self-driving road environment and a severity of a
lighting condition.
Further, in the driver's steering wheel operation detecting step,
when it is detected that the driver has not applied the effective
torque to the steering wheel, the steering controller may control
the turning angle of the steering wheel to reach the expected
turning angle of the self-driving system.
According to another aspect of the present invention, a steering
control system of a vehicle is provided, the system including:
an expected vehicle steering angle computation unit for obtaining
information about an expected steering angle of a vehicle based on
an automatic planning control operation;
a driver's operation detection unit for detecting whether an
effective torque is applied to a steering wheel by a driver;
and
a self-driving intent prompt torque determination unit for, when it
is detected that the driver has applied the effective torque to the
steering wheel, computing a difference between a turning angle of
the steering wheel controlled by the driver and the expected
steering angle of the vehicle, and determining a self-driving
intent prompt torque according to the difference, wherein the
self-driving intent prompt torque is to he applied to a steering
system.
Further, the self-driving intent prompt torque determined by the
self-driving intent prompt torque determination unit may
include:
a larger self-driving intent prompt torque determined when the
difference is larger, wherein the self-driving intent prompt torque
is opposite to a torque that the driver needs to provide, and thus
if the difference is larger, the torque that the driver needs to
provide is larger.
Further, when the driver has applied the effective torque to the
steering wheel, the steering torque applied to the steering wheel
includes a steering torque applied by the driver, a steering
assistance torque of a vehicle steering assistance system and the
self-driving intent prompt torque.
Further, the self-driving intent prompt torque determination unit
may determine the self-driving intent prompt torque .tau..sub.c
based on the following formula:
.tau..sub.c=-sig(.tau..sub.driver)f(fabs(.DELTA..beta.))
wherein .DELTA..beta. may be determined based on the following
formula: .DELTA..beta.=.beta..sub.e-.beta..sub.driver
wherein .tau..sub.driver denotes a torque currently applied by the
driver, .beta..sub.e denotes an expected turning angle of
self-driving, .beta..sub.driver denotes a turning angle where the
steering wheel is located, and sig(.tau..sub.driver) denotes the
direction of the torque currently applied by the driver;
f is a positive correlation function of an absolute value of
.DELTA..beta. and may satisfy the following conditions:
.times..function..ltoreq..times..times..function..tau..ltoreq..times..ti-
mes..function..tau. ##EQU00002##
wherein .tau..sub.eps denotes a steering assistance torque.
Furthermore, the steering control system may further include a
self-driving system operating status determination unit for
determining a reliability status of operations of the self-driving
system, wherein:
the self-driving intent prompt torque determination unit increases
the self-driving intent prompt torque determined according to the
difference and outputted by a steering controller in response to
determining that an operating status of the self-driving system is
a high-reliability status; or
the self-driving intent prompt torque determination unit decreases
the self-driving intent prompt torque determined according to the
difference and outputted by the steering controller when the
operation of the self-driving system is determined to be in a
low-reliability status.
Further, the method for determining the reliability status of the
operations of the self-driving system may be based on a complexity
of a current self-driving road environment and a severity of a
lighting condition.
Moreover, the steering control system may further include an
automatic steering control unit for controlling the turning angle
of the steering wheel to reach the expected turning angle of the
self-driving system when the driver's operation detection unit
detects that the driver has not applied the effective torque to the
steering wheel.
Compared with the conventional EPS systems, the steering control
method and control system for self-driving of a vehicle according
to the embodiments of the present invention can inspect whether a
driver's operations are consistent with self-driving expectations g
according to computation results of the self-driving system, and
determine a self-driving intent prompt torque to be applied
according to a degree of inconsistency. As such, the steering
control method and control system disclosed herein can prompt the
driver of the steering intent of the self-driving system, instead
of passively assisting the driver's operation only according to the
driver's operations as in the EPS systems. Also, compared with the
existing self-driving steering control systems, they can affect the
torque to be applied by the driver through the change of the
self-driving intent prompt torque, thereby prompting the human
driver of the steering intent of the self-driving system, while
ensuring the coexistence of the human driver and the self-driving
to avoid conflicts or exit of the self-driving state due to the
difference between the driver's steering intent and the
self-driving steering intent in the past.
The steering control method and the steering control system
according to the present invention may affect a human driving
operation by changing the torque mode according to the expected
steering angle computed by the self-driving system. The driver will
not be forced to change his/her steering operations but can be
prompted with a recommended driving behavior from the self-driving,
and in most cases, the driver can participate in the process of
steering control with nearly no operation, thereby improving the
safety and comfort of a driving experience.
BRIEF DESCRIPTION OF THE DRAWINGS
These and/or other aspects and advantages of the present invention
will become clearer and be understood more easily from the
following detailed description of the embodiments of the present
invention in combination with the accompanying drawings, in
which:
FIG. 1 is a flow chart of a steering control method for
self-driving of a vehicle according to an embodiment of the present
invention;
FIG. 2 is a structure diagram of a steering control system for
self-driving of a vehicle according to an embodiment of the present
invention;
FIG. 3 is a schematic structure diagram of a steering control
system 300 including an automatic steering control unit according
to an embodiment of the present invention; and
FIG. 4 is an overview flow chart of a steering control method for
self-driving of a vehicle according to an embodiment of the present
invention.
DETAILED DESCRIPTION OF EMBODIMENTS
In order that those skilled in the art better understand the
present invention, the present invention will be further described
in detail below in combination with the accompanying drawings and
specific embodiments.
FIG. 1 is a schematic block diagram of a steering control system
100 for self-driving of a vehicle according to an embodiment of the
present invention.
The steering control system 100 may include the following units: a
driver's operation detection unit 110, an expected vehicle steering
angle computation unit 120, and a self-driving intent prompt torque
determination unit 130.
Optionally, the steering control system 100 may further include a
steering torque application unit 140.
The driver's operation detection unit 110 may be configured to
detect whether an effective torque is applied to a steering wheel
by a driver.
Generally, a torque sensor is provided on the steering wheel. When
the driver turns the steering wheel, the torque sensor may detect a
torque input. At this time, it is determined that the driver is
operating the steering wheel, that is, an effective torque is
applied to the steering wheel. If the torque sensor does not detect
a torque input, it may be determined that the driver does not
operate the steering wheel, that is, no effective torque is applied
to the steering wheel.
The expected vehicle steering angle computation unit 120 may be
configured to obtain information about an expected steering angle
of a vehicle based on an automatic planning control operation.
For example, the expected steering angle of the vehicle may be
obtained based on a planning control operation carried out
according to a sensing and positioning input.
The self-driving intent prompt torque determination unit 130 may be
configured to compute a difference between a turning angle of the
steering wheel controlled by the driver and the expected steering
angle of a vehicle and determine a self-driving intent prompt
torque according to the difference, when it is detected that the
driver has applied the effective torque to the steering wheel,
wherein the self-driving intent prompt torque is to be applied to a
steering system.
In one example, when the self-driving intent prompt torque
determination unit 130 determines a larger self-driving intent
prompt torque when the difference between the turning angle of the
steering wheel controlled by the driver and the expected steering
angle of the vehicle is larger when determining a self-driving
intent prompt torque, wherein the self-driving intent prompt torque
is opposite to a torque that the driver needs to provide, so that
the torque that the driver needs to provide is larger. Thus, when
the driver operates the steering wheel, as the steering wheel
gradually approaches the expected steering angle of the vehicle,
the driver may feel more and more labor-saving and can thus realize
that his driving process is consistent with the self-driving
control intent. Otherwise, when the steering angle gradually
deviates from the expected steering angle, the driver may feel more
and more laborious and can thus realize that his driving process is
contrary to the self-driving control intent.
After the driver realizes the self-driving control intent, he can
determine whether he made a mistake in the previous operation. If
he confirms that he did not make a mistake, he can make adjustments
in time. If he confirms that his operation has not been mistaken,
he can, for example, ignore the self-driving control intent,
continue to operate as originally planned or temporarily turn off
the self-driving control (for example, via an option button for
exiting the self-driving control provided by the vehicle), and
concentrate on driving the vehicle according to the driver's own
intent.
In the conventional EPS systems, the torque for driving the
steering of the wheel is composed of a steering torque applied by
the driver and a steering assistance torque of the steering
assistance system.
According to the steering control system of the embodiment of the
present invention, when it is detected that the driver has applied
the effective torque to the steering wheel, the self-driving system
and the driver jointly participate in the steering process by
applying the self-driving intent prompt torque.
According to an embodiment of the present invention, when the
driver has applied the effective torque to the steering wheel, the
steering torque applied to the steering wheel by the steering
torque application unit 140 may include a steering torque applied
by the driver, a steering assistance torque of a vehicle EPS system
and the self-driving intent prompt torque.
That is, the steering torque at this time may be determined based
on the following formula (1):
.tau.=.tau..sub.driver+.tau..sub.eps+.tau..sub.c (1)
wherein .tau..sub.driver is a driver's steering torque,
.tau..sub.eps is an EPS steering assistance torque, and .tau..sub.c
is a self-driving intent prompt torque.
When the specified steering angle is zero, the torque may be zero,
the counterclockwise torque is positive, and the clockwise torque
is negative.
In one example, the self-driving intent prompt torque .tau..sub.c
may be determined based on the following formula (2):
.tau..sub.c=-sig(.tau..sub.driver)f(fabs(.DELTA..beta.)) (2)
wherein .DELTA..beta. is determined based on the following formula
(3): .DELTA..beta.=.beta..sub.e-.beta..sub.driver (3)
wherein .tau..sub.driver denotes a torque currently applied by the
driver, .beta..sub.e denotes an expected turning angle of
self-driving, .beta..sub.driver denotes a turning angle where the
steering wheel is located, and sig(.tau..sub.driver) denotes the
direction of the torque currently applied by the driver;
f is a positive correlation function of absolute value of
.DELTA..beta. and may satisfy conditions (4):
.times.
.function..ltoreq..times..times..function..tau..ltoreq..times..ti-
mes..function..tau. ##EQU00003##
wherein .tau..sub.eps denotes a steering assistance torque, and
fabs(.tau..sub.c) denotes an absolute value of .tau..sub.c.
According to the steering control system of the embodiment of the
present invention, after the self-driving intent prompt torque is
increased, the system may make the driver feels that it is more
labor-saving to control the steering wheel to turn to the expected
steering angle of the self-driving system, and that it is more
laborious to control the steering wheel to turn opposite to the
expected steering angle of the self-driving system.
In one example, the steering control system may adopt a
self-driving intent prompt torque strategy in consideration of an
operating state of the self-driving system in addition to the
difference between the driver's operation and the expected turning
angle of the self-driving system, and may change the magnitude of
the self-driving intent prompt torque according to the reliability
of the self-driving state, thereby changing the degree of
participation of the machine driving in the driving process. The
steering control system that determines the self-driving intent
prompt torque in consideration of the operating state of the
self-driving system will be described below in combination with
FIG. 2.
FIG. 2 shows a structure diagram of a steering control system 200
that determines a self-driving intent prompt torque in
consideration of an operating state of a self-driving system
according to another embodiment of the present invention.
As shown in FIG. 2, compared with the steering control system 100
of FIG. 1, the steering control system 200 further includes a
self-driving system operating state determination unit 250 besides
the driver's operation detection unit 210, the expected vehicle
steering angle computation unit 220, the self-driving intent prompt
torque determination unit 230 and the optional steering torque
application unit 240. The functions and working principles of the
driver's operation detection unit 210, the expected vehicle
steering angle computation unit 220 and the steering torque
application unit 240 are similar to those of the corresponding
units of FIG. 1, and are not redundantly described herein. The
driving system operating state determination unit 250 and the
self-driving intent prompt torque determination unit 230 will be
mainly described below.
The self-driving system operating state determination unit 250 may
be configured to determine a reliability status of operation of the
self-driving system. For example, the self-driving system operating
state determination unit 250 may determine a reliability status of
operation of the self-driving system in combination with the
surrounding environment (geography, weather, lighting, etc.) where
the vehicle is located and/or feedback given by the driver,
etc.
For example, if the self-driving system detects that the current
environment is complex or the lighting condition is bad, the
self-driving system operating state determination unit 250 may
determine that there may be a high probability that the
self-driving system is in a low-reliability operating state.
Alternatively, if the self-driving system detects that the current
environment is simple and the lighting condition is good, the
self-driving system operating state determination unit 250 may
determine that the self-driving system is in a high-reliability
operating state.
When the self-driving system operating state determination unit 250
determines that there is a high probability that the self-driving
system is in a low-reliability operating state, the self-driving
intent prompt torque determination unit 230 may reduce (lower) the
amplitude of the self-driving intent prompt torque, and the system
at this time may be similar to the conventional EPS systems.
Alternatively, when the self-driving system operating state
determination unit 250 determines that there is a high probability
that the self-driving system is in a high-reliability operating
state, the self-driving intent prompt torque determination unit 230
may increase the magnitude of the self-driving intent prompt torque
to provide an obvious enhanced driving experience for the driver's
steering operations.
As an example, the steering control system for self-driving of the
vehicle according to an embodiment of the present invention may
further include an automatic steering control unit for, when the
driver's operation detection unit does not detect that the driver
has operated the steering wheel, i.e., the driver has not applied
the effective torque to the steering wheel, controlling the turning
angle of the steering wheel to reach the expected turning angle of
the self-driving system, and the automatic steering control unit at
this time is consistent with the conventional self-driving steering
control system in function.
FIG. 3 is a block diagram schematically showing a steering control
system 300 including an automatic steering control unit according
to an embodiment of the present invention.
Compared with the steering control system 200 of FIG. 2, the
steering control system 300 of FIG. 3 may further include an
automatic steering control unit 360. The automatic steering control
unit 360 may receive the monitoring result of the driver's
operation detection unit 310, and controls the steering torque
application unit 340 to apply a torque corresponding to the turning
angle determined by the self-driving system in the expected
direction of the vehicle to the steering wheel when the driver's
operation detection unit 310 does not detect that the driver has
operated the steering wheel, i.e., the driver has not applied the
effective torque to the steering wheel, so that the steering wheel
may reach the expected turning angle of the self-driving system.
The torque applied by the steering torque application unit 340 at
this time does not include the aforementioned torque applied by the
driver, the EPS assist torque and the self-driving intent prompt
torque.
A steering control method in accordance with the above-described
steering control system according to an embodiment of the present
invention will be described below in combination with FIG. 4.
FIG. 4 is a generic flow chart of a steering control method for
self-driving of a vehicle according to an embodiment of the present
invention.
As shown in FIG. 4, an embodiment of the present invention provides
a steering control method for self-driving of a vehicle, including
steps S410 to S430.
In step S410, information about an expected steering angle of a
vehicle may be obtained based on an automatic planning control
operation.
In step S420, whether an effective torque has applied to a steering
wheel by a driver is detected.
In step S430, when it is detected that the driver has applied the
effective torque to the steering wheel, a difference between a
turning angle of the steering wheel controlled by the driver and
the expected steering angle of the vehicle is computed, and a
self-driving intent prompt torque is determined according to the
difference between the two and applied to a steering system.
According to the steering control method of the embodiment of the
present invention, when it is detected that the driver has applied
the effective torque to the steering wheel, the self-driving system
and the driver jointly participate in the steering process by
applying the self-driving intent prompt torque.
In one example, in step S430, when the self-driving intent prompt
torque is determined according to the difference between the
turning angle of the steering wheel controlled by the driver and
the expected steering angle of the vehicle, and the difference
between the turning angle of the steering wheel controlled by the
driver and the expected steering angle of the vehicle is larger, a
larger self-driving intent prompt torque is determined, and the
self-driving intent prompt torque is opposite to a torque that the
driver needs to provide, so that the torque that the driver needs
to provide is larger.
Specifically, the steering torque applied to the steering wheel may
include a steering torque applied by the driver, a steering
assistance torque of a vehicle steering assistance system and the
self-driving intent prompt torque. That is, the steering torque T
at this moment may be determined based on the following formula:
.tau.=.tau..sub.driver+.tau..sub.eps+.tau..sub.c,
wherein .tau..sub.driver is a driver's steering torque,
.tau..sub.eps is a steering assistance torque, and .tau..sub.c is a
self-driving intent prompt torque. When the specified steering
angle is zero, the torque is zero, the counterclockwise torque is
positive, and the clockwise torque is negative. The computational
formula of the compensation torque, that is, the self-driving
intent prompt torque .tau..sub.c, is determined based on the
following formula:
.tau..sub.c=-sig(.tau..sub.driver)f(fabs(.DELTA..beta.))
wherein .DELTA..beta. is determined based on the following formula:
.DELTA..beta.=.beta..sub.e-.beta..sub.driver
wherein .tau..sub.driver denotes a torque currently applied by the
driver, .beta..sub.e denotes an expected turning angle of
self-driving; .beta..sub.driver denotes a turning angle where the
steering wheel is located, and sig(.tau..sub.driver) denotes the
direction of the torque currently applied by the driver;
f is a positive correlation function of an absolute value of
.DELTA..beta. and may satisfy the following condition:
.times..function..ltoreq..times..times..function..tau..ltoreq..times..ti-
mes..function..tau. ##EQU00004##
wherein .tau..sub.e, denotes a steering assistance torque, and
fabs(.tau..sub.c) denotes an absolute value of .tau..sub.c. It
should be noted that the steering torque .tau. required for
steering at a certain moment is definite, and is determined by a
resistance torque fed back by the ground. The self-driving intent
prompt torque is opposite to the driver's torque. Thus, when the
self-driving intent prompt torque is large (the difference between
the steering angle and the expected turning angle of the vehicle is
large), a larger driver torque is required to obtain the required
steering torque .tau.; as the steering angle changes, the
difference between the steering angle and the expected turning
angle of the vehicle changes, then the self-driving intent prompt
torque changes, and the torque that the driver needs to provide
also changes, thereby achieving the purpose of providing a
self-driving intent to the driver.
It can be clearly seen from the above formula and analysis that,
according to the steering control method of the embodiment of the
present invention; after the self-driving intent prompt torque is
increased, the driver may feel that it is more labor-saving to
control the steering wheel to turn to the expected steering angle
of the self-driving system, and it is more laborious to control the
steering wheel to turn opposite to the expected steering angle of
the self-driving system.
For example, it is assumed that according to the current steering
angle, the total steering torque is 4 Nm (Newton meters), wherein
the steering assistance torque is 3 Nm, and that when the
self-driving system is not started; the driver provides an
additional torque of 1 Nm. After the self-driving system is
started, if the difference .DELTA..beta. between the expected
turning angle of the self-driving system and the driver's turning
angle is 5 degrees, the self-driving intent prompt torque
.tau..sub.c is -1 Nm, then the torque that the driver needs to
provide is 2 Nm. When the difference .DELTA..beta. between the
expected turning angle of the self-driving system and the driver's
turning angle is increased to 10 degrees, the self-driving intent
prompt torque .tau..sub.c is -3 Nm, then the torque that the driver
needs to provide becomes 4 Nm. As a result, the driver needs to
provide a larger steering torque for maintaining the current
turning angle. Hence, when the difference .DELTA..beta. between the
expected turning angle of the self-driving system and the driver's
turning angle is large, the driver feels laborious, thereby being
able to realize the inconsistency between his current operation and
the expectation of the self-driving system.
According to the steering control method of the embodiment of the
present invention, in one example, the self-driving intent prompt
torque determination strategy may also consider the operating state
of the self-driving system besides the difference between the
driver's operation and the expected turning angle of the
self-driving system.
For example, a reliability status of operations of the self-driving
system can be determined according to the complexity of the current
self-driving road environment and the severity of the lighting
condition. For example, if the self-driving system detects that the
current environment is complex or the lighting condition is bad, it
may be in a low-reliability operating state. In such a case, the
amplitude of the self-driving intent prompt torque may be reduced
and the system may be similar to the conventional EPS systems.
Alternatively, if the self-driving system detects that the current
environment is simple and the lighting condition is good, it is in
a high-reliability operating state, and the amplitude of the
self-driving intent prompt torque is increased to provide an
obviously enhanced driving feel for the driver's steering
operation.
In the steering control method of the present embodiment, when it
is not detected that the driver has operated the steering wheel,
i.e., the driver has not applied the effective torque to the
steering wheel, the self-driving system controls the turning angle
of the steering wheel to reach the expected turning angle of the
self-driving system, and the self-driving system at this time is
consistent with the conventional self-driving steering control
system in function.
Compared with the conventional EPS systems, the steering control
method and control system for self-driving of a vehicle according
to the embodiments of the present invention can inspect whether the
driver's operation is consistent with the self-driving expectation
according to the computing result of the self-driving system, and
determine a self-driving intent prompt torque to be applied
according to the degree of inconsistency, thereby being able to
prompt the driver of the steering intent of the self-driving
system, instead of passively assisting the driver's operation only
according to the driver's operation as in the EPS system; and
compared with the existing self-driving steering control system,
they can affect the torque to be applied by the driver through the
change of the self-driving intent prompt torque, thereby prompting
the human driver of the steering intent of the self-driving system,
but ensuring the coexistence of the human driver and the
self-driving to avoid the conflict or exit of the self-driving
state due to the difference between the driver's steering intent
and the self-driving steering intent in the past.
The steering control method and the steering control system
according to the present invention affect a human driving operation
by changing the torque mode according to the expected steering
angle computed by the self-driving system. The driver will not be
forced to change his/her steering operation but can be prompted
with a recommended driving behavior from the self-driving, and in
most cases, the driver can participate in the process of steering
control with nearly zero operation, thereby improving the safety
and comfort of a driving process.
It should be noted that the vehicle in the description should be
understood in a broad sense, including various large, medium and
small vehicles, water vehicles, trans-atmospheric vehicles,
etc.
It should be noted that relevant steps of the method may be
performed locally in the vehicle, or in the cloud, or both locally
and in the cloud.
It should be noted that although the steps in the flow chart are
shown in a certain order, this does not mean that the steps can
only he performed in this order, but as long as there is no logical
interdependence between the steps, the steps may be performed in a
reverse order or in parallel.
The above-described embodiments of the present invention are
exemplary but not exhaustive and are not limited to the disclosure.
Many modifications and alterations will be apparent to those of
ordinary skill in the art without departing from the scope and
spirit of the embodiments described. Therefore, the scope of the
present invention shall be subjected to the scope of the
claims.
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